1) Field of the Invention
This invention relates to filament yarns that are low wicking. Such yarns are traditionally employed in weaving signs, banners, awning, tents and other products where moisture resistant yarn is important. In particular, filament yarns of the present invention have a wicking characteristic of about 6 mm or less, a contact angle of greater than or equal to about 65° but less than about 90°, and have a static voltage range of +/−400 volts (a voltage between −400 to +400). Such filament yarns are made using an aqueous dispersion of a specific fluorocarbon surfactant, or a mixture of a few specific surfactants, that is used to impart water and oil repellency to synthetic fibers. Known fluorocarbon surfactants that impart water and oil repellency to synthetic fibers are not capable of achieving the wicking angle, contact angle and static voltage mentioned previously.
2) Prior Art
Use of fluorochemical emulsions and specifically fluorocarbon surfactant emulsions to impart oil and water resistance to synthetic fibers is well known. These treatments can be applied in the form of a spin finish to impart moisture resistance in fabric made from the fiber or continuous filament. Its use as a spin finish for carpet fibers, for example, is to impart water and oil repellency to the synthetic fibers. The following prior art illustrate these technologies.
U.S. Pat. No. 6,536,804 to Dunsmore et al. relates to carpet fibers in which a spin finish is applied to the synthetic staple fibers (not continuous filament yarn) for creating a surface on the carpet that is water and oil repellent. As set forth in Examples 15-24 of this patent, fluorochemicals were components of the spin finish.
U.S. Patent Application Publication Number US 2003/0175514 to Hancock et al. discloses a low wicking type material that has use in fabrics, which are water repellent. Specific polymers disclosed are nylons, polyesters and polyolefins. This reference also discloses that a filament has a contact angle greater than or equal to 90° as measured by the method disclosed in the Journal of Colloid and Interface Science, 177, 579-588 (1996). This reference also discloses a filament having a coating thereon and wherein the contact angle of the coated filament is greater than or equal to 90°. The coating (described as the “second longitudinally-extending component of the filament”) can be virtually any halogenated polymer as disclosed in Paragraph 29.
Although theses prior art documents disclose fluorochemcial based finishes to polyester yarn that results in moisture resistance, they do not disclose wicking less than about 6 mm inches. For example, Honeywell has a product called WickGard™ Anti-Wick Finish. Honeywell advertises that the fabric wicking performance when WickGard™ Finish is employed on the fabric and cured at 155° C. for 15 minutes, is 6.4 mm maximum. Furthermore, the prior art documents disclose a static voltage operating range greater than 400 volts. Static voltage above +/−400 volts, requires that the yarn be processed in a humid atmosphere employing the addition of static eliminators to the processing equipment, and reducing the processing equipment speed by 30% or more. The polarity of the static voltage depends on the relative position of the yarn and the rubbing surface on the triboelectric series. On the other hand, continuous filament yarns having a static operating range of +/−400 volts permits the continuous filament yarns to be processed into a fabric in virtually any ambient air conditions, without the need of static eliminators in the fiber forming and fabric forming equipment, and because the continuous filament is drier, the processing equipment can be run at faster output.